Mass Effect 2: Arrival is set within the Milky Way galaxy during the 22nd century, where interstellar travel is possible through the use of mass transit devices called Mass Relays. Elite human soldier Commander Shepard is sent on a mission to rescue Dr. Amanda Kenson, an Alliance scientist being held captive by the batarians, an alien species opposing humanity. Kenson claims to have found evidence of an imminent invasion of Reapers, a highly advanced machine race of synthetic-organic starships encountered in the first Mass Effect game.Arriving in the batarian-owned Bahak system, Shepard infiltrates the prison and rescues Kenson, who explains that she discovered a Reaper artifact which gave her visions of the invasion. The Reapers plan to use the Bahak system's Mass Relay to quickly travel throughout the galaxy and conquer it, but she and her research team plan to stop it by crashing an asteroid into it. Shepard asks to see the proof and is taken to the artifact, which is located inside a complex on the surface of a large asteroid.
Upon arriving at the artifact, Shepard has a vision of the Reaper fleet approaching. Kenson and her entire team, however, turn out to have been indoctrinated from having spent too much time studying the artifact. She attacks Shepard, who is eventually overwhelmed by her soldiers. Upon awakening two days later, Shepard manages to escape and reach the control room, where he/she sets the asteroid on course to hit the Bahak system's relay. In retaliation, Kenson plans to destroy the asteroid by overloading the reactor core of the facility, but Shepard ultimately stops her. Shepard then contacts his/her starship and escapes shortly before the asteroid hits the Relay, resulting in the destruction of the entire Bahak system. Shepard is later met by Admiral Steven Hackett, their superior officer, who explains that he/she has to go to Earth and face the consequences, setting the stage for Mass Effect 3
Shepard the call for the Arrival mission on the Normandy. He have a short conversation with Admiral Hackett.
This unlocks the Viper Nebula, a system along the bottom fringe of the galaxy map. The Bahak system is fairly barren, as he might expect from a batarian-controlled area of space, and only Yunaca, the nearly-invisible planet third from its sun, has any mineral deposits worth collecting.
Arrival is a solo mission for Shepard.
